The present invention relates to a threadless pipe joint being coupled with a small metal pipe and capable of being used under high pressure as well as low pressure. The pipe joint of the present invention is particularly suitable for double-roll brazed steel pipes which are used as an automobile brake oil pipe.
The double-roll brazed steel pipe, as shown in FIG. 1a, is made from a steel strap previously copper-plated on its opposite surface by a process that is doubled-rolled in the tubular form and then passed through energized high-frequency electromagnetic coils where it is rapidly heated with the result that the face-to-face copper platings melt and join together. The seamline is then brazed.
In comparison with seamless steel pipes made by cold-drawing, the above-mentioned pipe is inexpensive and has a clean inner surface. Furthermore, it is possible to make thin-walled pipes that cannot be made by drawing. The pipe is also more reliable than butt-welded steel pipes. As compared with copper pipes, it, of course, is very inexpensive and is high pressure-proof. In spite of such advantages, the above-mentioned pipe cannot be joined by the conventional pipe joint due to its elongated seamlines on both the inner and outer surfaces thereof. The seamlines, which are the opposite sidelines of the original strap, are shown in FIG. 1b with reference to numerals 16 and 17. The pipe is primarily used as automobile brake oil pipes which are coupled with the joint in automobile factories, where its end portion is flared into a trumpet form and then dipped in a soldering bath to cover the seamline prior to coupling with the joint. This procedure requires too many man hours to be performed at any place other than the factory, so that pipes of this type are rarely used except for automobile piping parts.
It is the primary object of the present invention to provide a pipe joint assembly available for joining together double-roll brazed steel pipes as well as small diameter metal pipes such as copper pipes and aluminum pipes.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.